1. Field of the Invention
The present invention relates to a VOR monitoring receiving apparatus and VOR monitor receiving method for monitoring the operation of a very high frequency omnidirectional radio range (VOR) apparatus.
2. Description of the Related Art
Airports in various regions employ various types of equipment for assisting the landing of airplanes, such as passenger airplanes. For instance, a very high frequency omnidirectional radio range (VOR) device is included in the equipment (see, for example, radar technologies disclosed by Institute of Electronics, Information and Communication Engineers). VOR apparatuses provide direction information to airplanes utilizing the horizontal polarization of a signal with a frequency of 112 to 118 MHz.
To utilize the VOR apparatuses, they are required to operate stably. In the prior art, a VOR monitoring receiving apparatus is used, which receives a field signal from a VOR apparatus and monitors it to confirm the operation of the VOR apparatus. To confirm whether a built-in monitoring receiving circuit is operating normally, the VOR monitoring receiving apparatus uses a self-check signal.
While the built-in monitoring receiving circuit is receiving a self-check signal, the VOR monitoring receiving device cannot receive a to-be-monitored field signal, and hence cannot detect any abnormality. In light of this, a technique of displaying, on a single screen, a window for a field signal and a window for a self-check signal may be employed as in standard computers (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 5-204584). In this case, however, the control of a memory for holding the windows, and the window task control and structure are inevitably complex.